Field of the Invention:
The present invention relates to a switch unit which, for example, is attached to the steering wheel of a vehicle.
Description of the Related Art:
Conventionally, a switch unit (composite switch) has been known, which is made up from a combination of a rotary switch that rotates a rotating member (wheel) along an outer peripheral surface thereof, and a seesaw switch that allows a swing member (knob) to swing about a support shaft.
For example, as shown in FIGS. 5 and 6, a switch unit 100 disclosed in Japanese Laid-Open Patent Publication No. 2002-150888 is equipped with a rotary switch 104 having a wheel 102, and a seesaw switch 108 having a knob 106. The knob 106 is disposed in surrounding relation to the wheel 102, and is capable of swinging in a circumferential direction of the wheel 102.
In the switch unit 100, the wheel 102 is disposed in an opening 110 provided in the center of the knob 106. A substrate 114 is provided inside a cover 112, and a holder 116 is provided on the substrate 114. A rotary shaft 118 of the wheel 102 is fixed rotatably to the holder 116. Both ends of the rotary shaft 118 are inserted through shaft holes 120 of the knob 106. The knob 106 is supported so as to be capable of swinging with respect to the rotary shaft 118.
An amount of rotation and a direction of rotation of the wheel 102 are detected by a rotary encoder 122. A pressing operation of the wheel 102 in a direction toward the substrate 114 is detected by a tact switch 124 for the rotary switch, which is in contact with the rotary shaft 118. A rocking operation of the knob 106 is detected by tact switches 126 for the seesaw switch, which are provided at a lower end of the knob 106.
Stoppers 128 and plate springs 130 are disposed between the tact switches 126 for the seesaw switch and the lower ends of the knob 106. A rocking motion of the knob 106 is regulated within a predetermined range by the stoppers 128, and after being swung, the knob 106 is capable of returning to its initial position (neutral position) by the plate springs 130.